Shadow the Hedgehog is a 2005 platform game developed by Sega Studios USA, the former United States division of Sonic Team, and published by Sega. It is a spin-off from the Sonic the Hedgehog series and follows Shadow the Hedgehog, a creation of Doctor Eggman's grandfather, Prof. Gerald Robotnik, as he attempts to learn about his past while suffering from amnesia. Shadow the Hedgehog introduces third-person shooter elements and nonlinear gameplay to the Sonic franchise. To defeat enemies, Shadow can use various weapons and special attacks, and most levels have three possible missions that the player may choose to complete. The missions completed determine the game's plot and subsequently playable levels. The development team wanted to make a game featuring Shadow to capitalize on the character's popularity and resolve plot mysteries that began with his introduction in Sonic Adventure 2. It was written and directed by Takashi Iizuka, produced by Yuji Naka, and scored by Jun Senoue. Iizuka, who targeted a younger audience with previous Sonic games, strove to attract an older audience with Shadow the Hedgehog; Shadow's character also allowed the team to use elements otherwise inappropriate for the series. It received a E10+ rating from the ESRB for its mild use of profanity and fantasy action violence, becoming the first game in the series to have the rating. It is also the first game in the series to use the 4Kids voice actors from Sonic X. The game was revealed at the March 2005 Walk of Game event, and it was released for the GameCube, PlayStation 2, and Xbox in North America and in Europe in November 2005 and in Japan the following month. Shadow the Hedgehog received generally unfavorable reviews from critics, who criticized its controls, mature themes, level design, and addition of guns and other weapons to traditional Sonic gameplay. However, some praised its replay value. Despite negative reviews, the game was commercially successful, selling 2.06 million copies by March 2007.